There is something to be said for having a celebrity parachute herself into your constituency. No protracted fussing on the doorstep. Only: "Hello, I'm from me."

The policy conversation is also brief. As it's impossible to know what line the celebrity might take in a parliamentary vote except, perhaps, where higher rate taxation is concerned, these candidates ask only that you believe in their niceness. In the case of Martin Bell, it helped that he wore a white suit and was brave. Esther Rantzen, in what must be an inviting prospect for Luton South, prefers the symbolic effect of her legs, in fishnet tights. "I weigh about the same as I did at 30," she said, flashing them last year in the Daily Mail. "I pride myself that I have the spring, bounce and youthful energy of a lamb."

So can she depend on your vote? This may depend on whether you remember Esther sharing a recent compliment from her gynaecologist, following a routine examination. "It's all in excellent working order; don't waste it."

Last week, the celebrity asked readers to disregard what might look like the comparative atrophy of her political responses, progressing over four or five decades. "I have always been fascinated by politics," she insisted, "but never found any one party manifesto that I could swallow whole." Where individual politicians are concerned, however, there is some evidence that she has leant towards the Conservative. Older readers may remember the late Sir Nicholas Fairbairn, the tartan-suited dipsomaniac and Tory MP for Kinross and Western Perthshire. He makes a surprise appearance in an early section of Esther, the autobiography, a book which must serve, for the time being, as Rantzen's manifesto.

"How did he seduce me?" Rantzen asks, in a passage which one of her admirers, Craig Brown, has already rendered into the libretto form, in the event of its inspiring a modern opera. "He took me to lunch at the Ritz. He gave me a long-stemmed red rose and ordered Beluga caviare and Krug champagne. I had never eaten Beluga caviare by the potful before. The Beluga consisted of huge, succulent globes that exploded on the tongue. If ever there was an aphrodisiac meal, this was it. Nicholas took me to some lord's house where he was staying and the rest was inevitable."

As persuasive as this might be to a certain kind of floating voter, it resists comparison with standard party literature relating to schools and hospitals. Perhaps it would be fairer, in future, if celebrities could stand against one another: Barbara Windsor against Gloria Hunniford, for example, Anne Robinson v Judy Finnigan.

Until then, as Esther Rantzen has pointed out, there is a danger she might be discriminated against, come election time, just for being famous. "The first decision was to assess whether voters there would welcome my intervention," she writes of Luton South. "Would they share the view of a few professional politicians who have begun to sneer about a 'celebrity', a mere 'TV personality', muscling in on their act." To visit Luton incognito was clearly out of the question. "Communication," she says, "is an important part of a politician's role."

It is a measure of her skill, in this department, that so many of us are familiar with Esther's work as the face of Accident Advice Helpline. "Have you been injured in an accident that wasn't your fault?" This is something that the voters of Luton South might want to think about. Can no one help them with Esther, on a no-win, no-fee basis?

You might reflect, as a Luton South voter, that it is enough for your MP (Margaret Moran) to go awol following her Southampton disgrace. Must your constituency be further punished, as the arena in which Britain's rebellious tradition finds its ultimate expression: a demand for government by celebrity?

But, given the existing number of celebrity satellites, with Carol Vorderman (popular voice of debt consolidation), appointed Cameron's maths mistress, and Mariella Frostrup adding lustre to appearances by Gordon Brown, the scandal has only accelerated an inevitable movement towards the centre of things. And if Joanna Lumley is too intelligent to lead them into the coming election, Rantzen is by no means the worst alternative. Alan Sugar, Richard Branson, and Simon Cowell are among the attention-seeking plutocrats already mentioned as preferable to your resident parliamentary shyster. To the point that, for the first time since the whole unravelling began, one begins to feel a sneaking sympathy for the average parliamentary kleptomaniac. He is unlikely, after all, to have diverted the profits of his soft-furnishing scam into an account in the Virgin Islands. In fact, most pretenders to an independent parliamentary career, famous or not, will need to have enriched themselves somehow for that purpose, in ways which may never be examined by the Daily Telegraph

Even if one were satisfied, where individuals such as Mr Branson are concerned, with the self-declaration of philanthropy, there would remain some doubt over their potential to change things, once they had also changed habitat. Joanna Lumley, for example, triumphed over Phil Woolas because she, unlike him, is famous, and uncontaminated by politics. As Joanna Lumley, MP, she would face a horrifying reverse: Mr Woolas, useless thesp that he is, would be allowed to patronise her. How, then, would she continue to do good?

Ms Rantzen is not alone in believing that a contingent of random, unpredictable show-offs would be an ornament to the house. "Voters can trust independent MPs not to be motivated by a lust for power," she explains, "as they'll never achieve office." Yet the set-up does not sound dissimilar from I'm a Celebrity... Get me Out of Here. Can we trust celebrity independents not to regard political showtime as a natural next step for any reality-TV specialist for whom Strictly Come Dancing is but a distant memory?

If the number of plausible MPs is now alarmingly diminished, the pool of acceptable celebrity choices is, surely, smaller still. So much so that one cannot even propose a straightforward life-swap whereby, for example, the Ivy acquires Alan Duncan and Hazel Blears, in exchange for Graham Norton and Kate Winslet. Who would you give for Jonathan Ross? Anthony Steen and Stephen Fry cancel one another out.

The one kind of MP who cannot be parachuted into a constituency is, by definition, the one you might actually want: the local candidate. It would help if they were also honest, idealistic, practical and diligent. But perhaps the academics who study human venality are right. Such people never existed. Everyone is on the take. Everything the government says about the voluntary sector is bilge.

You are less likely to find an ordinary, incorruptible individual prepared to serve her community than to see a person in fishnets plummeting from the sky. If she asks if you have recently been injured in an accident that wasn't your fault you will know it is Esther Rantzen. Representing herself.